1. Field of the Invention
This invention relates to a semiconductor device having a package construction, and a manufacturing method for the device.
2. Description of the Related Art
There have been mounting demands for smaller and thinner external dimensions (also called “package size”) for semiconductor devices mounted in portable equipment and other electronic products. This has been attended by increasing interest in CSPs (Chip Size Packages), which are semiconductor devices packaged with external dimensions substantially the same as the external dimensions of a semiconductor chip.
Among CSPs, WCSPs (Wafer-level Chip Size Packages), in which devices are finished up to the external terminal formation process in the wafer state and dicing is then performed to obtain dies, are attracting attention as a form enabling low manufacturing costs.
In WCSPs, a cut surface formed by dicing or similar becomes the side plane of each package. Consequently in a WCSP, the insulating film (for example, a polyimide film) on the passivation film of the substrate is also exposed on the side face. However, in general the above insulating film is hydrophilic, so that moisture penetrates into the package via the exposed insulating film, and there is the problem that wires and other conductive members are corroded.
Various constructions have been proposed to suppress the penetration of moisture from the hydrophilic insulating film into the package interior, and to suppress the degradation of package reliability.
For example, a construction has been proposed in which a passivation film and polyimide film or other insulating film are formed on the wafer, and after the dicing process, the side faces of the insulating film are positioned further inside from the cut surfaces which are to become the package side faces (for example, Japanese Patent Kokai No. 2003-124392; hereafter called “reference 1”).